1. Field of the Invention
The present invention relates to a lithium battery provided with a positive electrode, a negative electrode, a non-aqueous electrolyte, and a battery separator separating the above-mentioned positive electrode and negative electrode in a battery case, and battery polymeric materials employed for a battery separator separating the positive electrode and the negative electrode and a battery insulating packing sealing the battery case in a lithium battery. More particularly, the present invention is characterized in that discharge characteristics and the like of a lithium battery are prevented from being degrade even when the lithium battery is exposed to high temperature conditions, such as when the lithium battery is put into a reflowing furnace to be automatically soft-soldered.
2. Description of the Related Art
In recent years, a lithium battery employing a non-aqueous electrolyte to utilize oxidation and reduction of lithium ions have begun to be used as one of new-type lithium batteries having high power and high energy density.
Such a lithium battery employs the non-aqueous electrolyte as described above, and thereby evolution of hydrogen and oxygen due to a positive electrode and a negative electrode reacting during storage is restrained. Therefore, the lithium battery has begun to be used as an electric source for emergency such as for memory-backup and the like.
In the above-mentioned lithium battery, a positive electrode, a negative electrode and a non-aqueous electrolyte are generally contained in a battery case. In the lithium battery as described above, polymeric materials are employed for a battery separator separating the positive electrode and the negative electrode and a battery insulating packing electrically separating the battery case.
Further, in employing the lithium battery as an electric source for emergency such as for memory-backup and the like as described above, it is attempted that the lithium battery is put into a reflowing furnace to automatically soft-solder a lead terminal thereof onto a printed board.
When the lithium battery is put into a reflowing furnace to automatically soft-solder the lead terminal thereof onto the printed board as described above, the lithium battery is exposed to high temperature in the reflowing furnace and is usually kept under the high temperature conditions of 250° C. for about ten seconds.
However, when the lithium battery is kept under high temperature conditions of 250° C. for about ten seconds as described above, there exists a problem that the non-aqueous electrolyte in the battery case of the lithium battery reacts with the above-mentioned battery separator and the battery insulating packing which are formed by polymeric materials, whereby various performances of the lithium battery such as discharge capacity and the like are degraded.